Of same place



(No Model.)

W: W: PARTY LINE TELEPHONE APPARATUS.

No. 561,498. Patented June 2, 1896.

Inventdr: ZUZZZz'am Z0264)? JZ-Zvmzeys.

llNiTED STATES ATENT FFicE,

W'ILLIAM W. DEAN, OF ST. LOUIS, MISSOURI, ASSIGNOR TO THE BELL TELE- PHONE COMPANY OF MISSOURI, OF SAME PLACE.

PARTY-LINE TELEPHONE APPARATUS.

SPECIFICATION forming part of Letters Patent No. 561 ,498, dated June 2, 1896.

Application filed March 2 8, 1 8 9 6.

To all whom it may concern.-

Be it known that I, XVILLIAM \V. DEAN, a citizen of the United States, residing in the city of St. Louis, State of Missouri, have invented a certain new and useful Improvem ent in Party-Line Telephone Apparatus, (Case No. 8,) of which the following is afull, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

My invention relates to telephone-exchange systems in which party lines, one or more, are used with other telephone-lines having the ordinary equipment. IIeretofore in such systems where party lines have been employed and the transmitter-battery is centralized each subscriber has been required, though desiring connection With another station of his own line, to first call the central oflice in order that the common battery at the central station might be connected to supply the transmitter'circuits and the station wanted signaled by the central-office operator.

It sometimes is found specially desirable.

.or any one of the stations may call up the central office and be put into communication with any of the other telephone-lines of the system in the ordinary manner, as desired.

As to the priorvart I would refer topatents heretofore granted me as follows: No. 541,077, dated June 18, 1895; No. 546,731, dated September 24, 1895, and No. 549,477, dated Nocentral office, I provide a hand-magneto at snaln. 585,183. (No model.)

each of the substations, and at the central office I leave one of the limbs of the circuit of the party line open to prevent the generator-current sent from any one of the partyline stations from being shunted away from the high-resistance bells of the different party-line stations. I place in the branch of the circuit leading to the line from the centralized battery an electromagnetic circuitclosing device whereby the normally open limb of the party line is automatically closed whenever the telephone-switch of the subscriberss station of the party line is operated to close the circuit of the telephone-line through the transmitter-circuit to ground, as when the telephone is removed from the switch. I also place in the loop about the party telephone-line, which is connected with the circuit-closing device or relay, a retardation-coil, the ground branch leading through the electromagnet of the said relay and through the individual annunciator to the centralized battery being connected to the center of the coil of the retardation-coil. The retardation-coil prevents the voice-currents from being shunted from the receiving-telephones when two subscribers of the party line are talking with one another.

My invention will be, more readily understood by reference to the accompanying drawing, iii which I have illustrated an ordinary telephone-lineand a party line equipped with improvements connected to the centralied battery and operators outfit at the cenural office. t Station A is connected with the central office by a telephone-line having two limbs or branches a and a From the switch I) at the central office connection is made through individual annunciator c and thence to the common or centralized battery cl. The telephone 6 of station A is shown hung upon the switch-lever e, and the circuits of the inductioncoil e and the transmitter-circuit e are open at said switch 6. On taking down the telephone 6 the circuit of battery d is closed through the individual annunciator c at the central office, the induction-coil c and the transmitter-circuit e to ground, substantially in the manner illustrated and described in my previous patents. The subscribers bell Loo 6 is bridged across the limbs a a in a wellknown way and is of high resistance-say one thousand ohms. The operator, seeing the shutter fall, inserts the answering-plug f in the spring-jack b and by depressing key f loops her telephone into the line of station A. The branch of said line containing individual annunciator c is thus disconnected and the clearing-out annunciator f brought into circuit, current from battery at being at the same time continued over limbs a a by means of the plug f and the strands of the cord connected therewith. The operator, on being informed of the connection desired by the subscriber at station A, connects with the switch of the line wanted by means of an swering-plug f and throws calling-current to line by depressing key f as is usual.

I will now describe the party-line equipment to which my invention particularly relates. The party line is connected to the switch g and may contain any desired number of stations. I have shown in the drawing only two of said stations 13 and B The party line consists of a metallic circuit composed of two limbs or branches g These limbs are branched to the different stations B BF, &c., as shown. The apparatus at each of the party-line stations may be the same the apparatus of an ordinary lineas, for example, station A, with the addition of a magneto or suitable source of signalingcurrent. Thus at station B, I have provided in the circuit of the bell h a hand magnetogenerator h, and at station B I have provided a magneto connected in a normally open bridge. Ipreferably employamagnetogenerator provided with a shunt or short circuit about' its coils, which short circuit is adapted to be opened automatically and held open when and while the machine is in operation, after the manner described and claimed in Letters Patent to Elisha Gray, No. 309,617, when the magneto is connected, as shown, at station B. WVhen connected in a normally open bridge, as shown, at station 13 the turning of the crank serves also to closethe circuit of the bridge in a well-known way. It will be observed that the limb g of the party telephone-line is extended from its line-spring of switch g by a branch 7.", which passes through half of the coil of the retardation-coil 7.5 and thence to the circuit-closer or relay M, which said branch is shown open. The limb g of said party line is extended from its terminal spring of switch g by branch Zthrough the other half of the retardation coil 70 to the relay orelectromagnetic circuitclosing device k Connection is made thence through thecoil of the electromagnet of the relay by wire Z through the individual annunciator Z of the party line to the centralized battery (1.

Suppose the-subscriber at station E wishes to. talk with subscriber at station B He simply turns his hand-generator h, thus ringing his own bell h and the bell 2' of station B Likewise any other bells connected in the circuit at other stations that may be upon the same line will be rung. Therefore, where there are a number of stationsfor example, four or siXone ring will be agreed upon to indicate one station, two rings another station, and so on. It will be observed that since the branch 70 is open the high-resistance bells of the subscribers stations will not be shunted by branches Z, extending from switch g. The subscriber at station B, having thus rung up the subscriber desired, takes his telephone on from the switch m, and the switch closes the limb g to ground at station 13, and immediately current from battery (Z passes through the circuit-closing device R and thereupon the branch 76 is directly and automatically connected with branch Z. The

' two limbs of the line will thus be united and balanced for conversation, and the battery- 1 currents will be directed over the two limbs g g to ground at station B and also over the transmitter-circuit of subscriber at station B who has answered, while the retardationcoil 70 will prevent loss of the undulatory voice-currents. The individual annunciator Z should be of a type which is kept in vibra tion when the circuit through the same is interrupted, as by repeatedly closing a switch. I prefer the form in which the shutter or target moves synchronously with the movement of the subscribers switch as the switch opens and closes the circuit. The operator will thus understand that a simple movement of the annunciator of a party line only indicates that the party line is being used between the stations thereof and will not regard such single movement. The individual annunciator at the same time, when held up by current flowing through the same, indicates to the operator that the line is busy.

A subscriber on a party line desiring the attention of the operator will repeatedly move his switch to attract the attention of the operator.

My invention has been found of especial advantage in connection with train-despatching, where the users at the different stations are skilled.

The apparatus which I have illustrated and described is such as I have found in every way eflicient and suitable for such service. The construction thereof, it is evident, may,

however, be varied without departing from.

my invention. For example, I have shown at station B the bell i in one bridge and the generator 41 in a separate bridge, the two bridges being in multiple. hen the connections are thus made, the generator will be normally open, the turningof the crank serving to complete its connection.

Other variations or modifications of the various circuits and of the construction of the apparatus will readily suggest themselves to those skilled in the art.

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. The combination with a metallic-circuit telephone-line having the two limbs thereof connected at the central office, each with a separate contact or line spring of the switch, of two or more loop-circuits from said line, each including a subseribers telephone outfit, branches or extensions of said circuit ex tending respectively from the contacts of said line-springs, one branch being connected through anelectromagnetic circuitclosing device and an individual annunciator to a centralized battery, and the other branch being normally open at the said circuit-closing device, whereby on closing the limb connected with the said battery to ground at either of the subscribers stations, the electromagnetic circuit-closing device is operated by the current derived from the battery to unite said branches or extensions; substantially as and for the purpose specified.

2. A metallic-circuit telephone-line c011- tainin g two or more subscribers stations, each of said stations being provided with switching apparatus for connecting the said mctallic circuit to ground, an electromagnetic circuit-closing device included in a branch or extension from one of said limbs to the central oifice, the other limb being normally open but adapted to be united electrically with the normally-closed limb automatically by the said electromagnetic circuit-closing device put into action by current caused to traverse the same when connection is made to ground at either of said stations; substantially as and for the purpose specified.

The combination with a metallic-circuit telephone-line extending to the central otfiee and provided with two or more subscribers stations thereon, of high-resistance signalbells, one at each of said stations, included in a bridge across the limbs of said metallic circuit, and a source of signaling-current at each of said stations, one limb of said circuit stat-ions for closing the circuit of said telephone-line through the induction-coil and transmitter-circuit of the station, in combination with branches or extensions from said limbs at the central office, an electromagnetic circuit-closing device, an individual annunciator and a battery permanently included in one of said branches; said electromagnetic circuit-c1osing device being adapted, when operated by the closing of the ground circuit at either of said stations, to complete the connection between the two limbs; substantially as and for the purpose specified.

5. A metallic-circuit telephone-line having two or more subscribers stations thereon, said line being provided with two limbs adapted to be temporarily united at the central oflice through branches or extensions thereof, said branches including a retardation-coil, a battery being connected at the central office to thecenter of said retardationcoil, whereby the metallic circuit thus formed is balanced, while voice-currents sent between any two stations on the line are prevented from being shunted; substantially as and for the purpose specified.

In witness whereof I hereunto subscribe my name this 18th day of March, A. D. 1896.

WILLIAM W. DEAN. Witnesses:

GEORGE P. BARTON, JOHN W. SINCLAIR. 

